by Lao-Tzu (Laozi) is available here in EPUB, AZW3, and PDF formats.

Book description: This is an important translation of Lao-Tzu's book which is a key scripture of Taoism. This translation by Victor H. Mair is based on the Ma-wang-tui manuscripts and includes notes on the text as well as an extensive commentary presenting the translator's research about the history of Lao-Tzu and the Tao Te Ching, its terminology, the parallel between Taoist practices (meditation and qigong) and Indian Yoga, and the relationship between Taoist religion and Buddhism as well as Hinduism (Brahmanism).